Hose with rubber and plastic

ABSTRACT

A hose is provided comprising a rubber backing layer directly bonded to a continuous polyamide layer without an intervening adhesive layer, wherein the hose exhibits increased low and high temperature capability and decreased permeation compared to standard automotive refrigerant hoses.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional application of U.S. application Ser.No. 15/806,129, filed Nov. 7, 2017, which is a continuation applicationof U.S. Application No. 14/483,813, filed Sep. 11, 2014, which claimsthe benefit of U.S. Provisional Patent Application Ser. No. 61/878,238,filed Sep. 16, 2013, each of which is hereby incorporated by referencein its entirety.

BACKGROUND

Hoses have uses in many industries, such as automotive, appliance,aerospace, and manufacturing industries. Many hoses experience high andlow temperatures and some come in contact with corrosive materials.Ideally, a hose is not significantly affected by changes in temperature,exposure to environmental moisture or by the type of fluid passingthrough the hose. Additionally, a hose loses utility if it becomespermeable to outside elements (ingression) or to fluid passing throughthe hose (effusion). Existing automotive hoses can exhibit undesirablepermeation relative to new refrigerants. A hose with increased low andhigh temperature capability and decreased permeation compared to currentautomotive refrigerant hoses is desirable.

SUMMARY

Adhesive used to bond a plastic layer to a rubber layer in standardrefrigerant hoses can result in spotty adhesion. In order to solve thisproblem, methods and compositions have been developed to provide directbonding of an EPDM rubber backing layer to a plastic veneer of arefrigerant hose, without an intervening adhesive layer. In someembodiments, hoses are provided that exhibit increased low and hightemperature capabilities and decreased permeation compared to standardrefrigerant hoses.

A hose is provided comprising at least two layers including a rubberbacking layer directly bonded to a polyamide (PA) layer. The rubberbacking layer is prepared from a rubber backing composition comprisingan ethylene propylene diene monomer (EPDM), a phenylenedimaleimide, anda maleated compound. In some embodiments, the hose comprises amultiplicity of layers. In some embodiments, the polyamide layer is acontinuous layer. In some embodiments, the maleated compound is amaleated polybutadiene. In some embodiments, the maleated compound ispresent in the rubber backing composition in a range from about 0.1 wt %to about 15 wt %; 0.5 wt %-10 wt %; or 3 wt %-7 wt % compared to thetotal weight of filled rubber backing composition. In some embodiments,a phenylenedimaleimide is present in the rubber backing composition atfrom about 0.1 wt %-5 wt %; 0.5 wt %-3 wt %; or 1.00 wt % -1.75 wt % ofthe total weight of the filled rubber backing composition.

In some embodiments, the rubber backing composition further comprises anantioxidant. In some embodiments, the rubber backing composition doesnot contain polypropylene.

In some embodiments, the rubber backing layer is prepared from a rubberbacking composition further comprising one or more fillers. In someembodiments, the rubber backing composition comprises one or morefillers selected from carbon black, silica, silicates, talc, aluminumsilicate, calcium carbonate, zinc oxide, titanium dioxide and stearicacid. In some embodiments, the rubber backing composition comprisesfiller in an amount from about 30-60 wt %, 40-60 wt %, or 45-60 wt %compared to the total weight of the rubber backing composition. In someembodiments, the ethylene propylene diene monomer (EPDM) is low ethyleneEPDM. In some embodiments, the low ethylene EPDM has no more than 60%ethylene.

In some embodiments, a hose is provided comprising a rubber backinglayer and a polyamide layer wherein the rubber backing layer is directlycovalently bonded directly to the polyamide layer without adhesive. Insome embodiments, the rubber backing composition does not contain apolyamide. In some embodiments, the rubber backing composition comprisesan organic peroxide.

In some embodiments, a hose is provided comprising a rubber backinglayer and a polyamide layer, wherein the rubber backing layer isprepared from a rubber backing composition comprising an organicperoxide that is selected from dicumyl peroxide and t-butyl cumylperoxide. In some embodiments, the rubber backing composition does notcontain polyvinyl butyral.

In some embodiments, a hose is provided comprising a rubber backinglayer and a polyamide layer, wherein the polyamide layer is preparedfrom a second composition polyamide composition comprising one or moreof polyamide 6,6; polyamide 6; polyamide 11; or polyamide 12. In someembodiments, the polyamide layer is prepared from a polyamidecomposition comprising polyamide 6,6. In some embodiments, the polyamidecomposition does not contain EPDM. In some embodiments, the polyamidelayer is a continuous layer. In some embodiments, the rubber backinglayer as provided herein, exhibits adhesion to a polyamide layer ofgreater than 10 lbf/in, when tested according to ASTM D413 as providedherein.

In some embodiments, a hose is provided comprising a rubber backinglayer directly bonded to a polyamide layer, wherein the hose comprisesat least five layers arranged in the hose's radial direction from theoutside inwards in the following order: a cover layer; a reinforcementlayer; the rubber backing layer; the polyamide layer; and a resistancelayer. In some embodiments, the hose comprises a multiplicity of layerswherein a continuous polyamide plastic layer is bonded directly to arubber backing layer without an intervening adhesive layer.

The hose provided herein comprising a continuous polyamide plastic layerbonded directly to a rubber backing layer without an interveningadhesive layer exhibits surprisingly improved properties including oneor more of improved adhesion between a rubber backing layer and apolyamide layer without employing an intervening adhesive layer,increased high and low temperature stability, decreased effusion,decreased permeation, and/or decreased moisture ingression, whencompared to standard automotive refrigerant hose GH134.

In some embodiments, the hose provided herein exhibits decreasedeffusion or permeation to a refrigerant, relative to a commerciallyavailable automotive hose when tested in accordance with SAE J2064. Insome embodiments, the hose provided herein, when tested according to SAEJ2064 at 80° C. ±2° C., exhibits a permeation value of less than 3kg/m2/yr for refrigerant R- 134a (1,1,1,2-tetrafluoroethane).

In some embodiments, the hose provided herein, when tested according toSAE J2064 at 80° C.±2° C., exhibits a permeation value of less than 3kg/m2/yr , or preferably less than 2 kg/m2/yr, for refrigerant R-1234-yf(2,3,3,3-tetrafluoropropene).

In some embodiments, the improved properties of the hose provided hereinare imparted due to an improved rubber backing layer is prepared from arubber backing composition comprising an ethylene propylene dienemonomer (EPDM), a phenylenedimaleimide, and a maleated compound. In someembodiments, the rubber backing composition surprisingly allows for ahigher filler load of up to 50 wt %, 55 wt %, or preferably up to 60 wt%of total weight of the rubber backing composition while retainingimproved properties relative to a standard R134 multi-refrigerant hose.

In some embodiments, a method is provided for bonding two layers of ahose comprising blending a first composition comprising ethylenepropylene diene monomer (EPDM), a maleated compound andphenylenedimalemide; and bonding said composition to a polyamide layer.

In some embodiments, a method is provided for directly bonding togethertwo layers of a hose, the method comprising blending a rubber backingcomposition comprising ethylene propylene diene monomer (EPDM), amaleated compound and a phenylenedimalemide; and bonding saidcomposition to a polyamide layer. In some embodiments, the blending isaccomplished using a Banbury mixer. In some embodiments, the rubberbacking layer is applied to the polyamide layer by press curing orextrusion. In some embodiments, the extrusion comprises shearing and isfollowed by vulcanizing of the green rubber backing layer. In someembodiments, the vulcanizing is performed at 300° F.-330° F.

In some embodiments, a method is provided for directly bonding twolayers of a hose, the method comprising blending a rubber backingcomposition comprising ethylene propylene diene monomer (EPDM), amaleated compound and a phenylenedimalemide; and bonding saidcomposition to a polyamide layer, wherein the polyamide layer isprepared from a polyamide composition comprising polyamide 6, 6. In someembodiments, the polyamide (PA) layer is a continuous layer. In someembodiments, the polyamide (PA) layer is an inner layer, and the rubberbacking layer is an outer layer. In some embodiments, the hoseconstruction could be a barrier design where the PA layer is disposedbetween the rubber backing layer and the cover layer.

In some embodiments, a method of making a hose is provided, the methodcomprising co extruding two or more polyamide layers onto a mandrel toform a veneer comprising an inner resistance layer and a polyamidelayer; blending a first composition comprising an ethylene propylenediene monomer (EPDM), maleic anhydride and phenylenedimalemide andextruding the first composition on top of the polyamide layer to form arubber backing layer; applying a reinforcement layer over the rubberbacking layer; extruding a cover layer over the reinforcement layer toform a green hose; vulcanizing the green hose; and expelling the hosefrom the mandrel. In some embodiments the extrusion comprises shearingand heating. In some embodiments, the vulcanizing occurs at 300-330° F.In some embodiments, the veneer is prepared by coextruding PA6 and PA6,6on the mandrel.

In some embodiments, a rubber backing composition is provided comprisingone or more ethylene propylene diene monomers (EPDMs), aphenylenedimaleimide, and a maleated compound. In some embodiments, therubber backing composition comprises one or more EPDMs in a range fromabout 20 wt % to about 60 wt %; about 25 wt % to about 55 wt %; about30% to about 45 wt %; 30 wt % to about 40 wt %; 30 wt % to about 35 wt%; or about 34 wt % to about 36 wt % compared to the total weight of thefilled rubber backing composition.

In some embodiments, the ethylene propylene diene monomer (EPDM) is lowethylene EPDM. In some embodiments, the low ethylene EPDM has no morethan 60% ethylene. In some embodiments, the maleated compound is presentin the rubber backing composition in a range from about 0.1 wt % toabout 15 wt%; 0.5 wt %- 10 wt %; or 3 wt % - 7 wt % compared to thetotal weight of filled rubber backing composition. In some embodiments,a phenylenedimaleimide is present in the rubber backing composition atfrom about 0.1 wt%-5 wt %; 0.5 wt %-3 wt %; or 1.00 wt %-1.75 wt% of thetotal weight of the filled rubber backing composition.

In some embodiments, the rubber backing composition comprises one ormore organic peroxides. In some embodiments, the composition comprisesan organic peroxide selected from dicumyl peroxide and t-butyl cumylperoxide. In some embodiments, the rubber backing composition furthercomprises one or more fillers. In some embodiments, the rubber backingcomposition further comprises one or more plasticizers. In someembodiments, the rubber backing composition comprises one or morefillers selected from carbon black, silica, silicates, talc, aluminumsilicate, calcium carbonate, zinc oxide, titanium dioxide and stearicacid. In some embodiments, the rubber backing composition comprisesfiller in an amount from about 30-60 wt %, 40-60 wt %, or 45-60 wt %compared to the total weight of the rubber backing composition. In someembodiments, the rubber backing composition does not contain polyvinylbutyral. In some embodiments, the rubber backing composition does notcontain a polyamide.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates one embodiment of a hose with a multiplicity oflayers including a rubber backing layer bonded directly to a continuouspolyamide layer.

FIG. 2 is a Pareto chart of the standardized effects on adhesion ofphenylenedimaleimide, the maleated compound, and EPDM polymers withsimilar ethylene percentages but varying viscosities, with analpha=0.04.

FIG. 3 illustrates main effects plots for adhesion (lbf/in), showing thedata means of the mixes used to produce the data in FIG. 2 for each ofthe HVA-2, maleated compound, and EPDM polymers with similar ethylenepercentages but varying viscosities .

FIG. 4 illustrates a regression analysis of varying the HVA-2concentration in an example embodiment on adhesion (lbf/in).

FIG. 5 illustrates a regression analysis of varying the maleatedcompound concentration (pph) in an example embodiment on adhesion(lbf/in).

FIG. 6 is a Pareto chart of the standardized effects on adhesion forconcentrations (pph) of polybutene plasticizer, paraffinic oilplasticizer, N330 carbon black and N650 carbon black, with analpha=0.05.

FIG. 7 is a main effects plot for adhesion (lbf/in), showing the meansof adhesion when various concentrations (pph) of polybutene plasticizer,paraffinic oil plasticizer, N330 carbon black and N650 carbon black werevaried.

FIG. 8 illustrates the tensile strength and percent elongation over timeof “green” samples of an example rubber formulation according to aformulation of Example 7 that were cured over a two month periodaccording to ASTM D3182.

FIG. 9 illustrates the percent compression of three different rubberbacking layers at −40° C. over time, after platen or steam curing.

DETAILED DESCRIPTION

As used herein, the terms “a” or “an” are defined as singular or plural.

As used herein, the term “about” means within ten percent (10%) of thegiven value, either ten percent more than the given amount or tenpercent less than the given amount, or both.

As used herein, the term “composition” refers to one or more of acompound, mixture, blend, alloy, polymer and/or copolymer.

As provide herein, ranges are intended to include, at least, the numbersdefining the bounds of the range.

FIG. 1 is an illustration of one embodiment of the present invention,where the embodiment includes a hose 100 with a multiplicity of layers.In this example, the layers include a cover layer 110, a reinforcementlayer 108, a rubber backing layer 106, a polyamide layer 104 and aresistance layer 102.

The rubber backing layer 106 is prepared from a rubber backingcomposition comprising ethylene propylene diene monomer (EPDM),N,N′-m-phenylenedimaleimide (HVA-2), and a maleated compound. The rubberbacking composition allows for direct bonding to polyamide without anintervening adhesive layer upon vulcanization. In some embodiments, therubber backing layer 106 is prepared from a composition comprising EPDM,HVA-2, a maleated compound and one or more each of fillers,plasticizers, vulcanizing agents, peroxides, and/or or antioxidants. Insome embodiments, the rubber backing layer 106 is prepared from acomposition that does not contain polyvinyl butyral (PVB). In someembodiments, the rubber backing layer is prepared from a compositionthat does not contain polypropylene. In some embodiments, the rubberbacking layer 106 is prepared from a composition that does not contain apolyamide.

EPDM rubbers are produced by polymerization of a mixture of ethylene andpropylene and optionally a diene in the presence of a Ziegler-Nattacatalyst, such as, for example, diethylaluminum chloride. Compressionset (C Set) is one of the primary characteristics of a rubber compounddirecting low temperature sealing capability. EPDM ethylene content isan important factor influencing this compression effect. As the ethylenecontent increases, a low-level of crystallinity develops above about55%-65%. If the ethylene/propylene ratio is about equal and thedistribution of both monomers in the polymer chain is random then theEPDM is amorphous. Polymers with ethylene content above 60% tend to showhigh compression set, while the amorphous (less than 60% ethylene)materials provide decreased set values at low temperatures.

In some embodiments, the rubber backing layer 106 is prepared from arubber backing layer composition comprising one or more low ethylenecontent EPDMs. In some embodiments, the EPDM is a low ethylene EPDMhaving less than about 60% ethylene content.

In some embodiments, the low ethylene EPDM is selected from an EPDMhaving an ethylene content in a range of from about 45 wt % to about 60wt % ethylene; about 50 wt % to about 60 wt % ethylene; or about 55 wt %to about 60 wt % ethylene content.

In some embodiments, the rubber backing layer composition comprises oneor more suitable commercially available EPDM products, such as, forexample Vistalon™ 2504 (an ethylene propylene diene terpolymer rubberhaving about 57.5 wt % ethylene content by ASTM D3900A, ExxonMobilChemical); Vistalon™ 2502 (an ethylene propylene diene terpolymer rubberhaving about 57.5 wt % ethylene content by ASTM D3900A, ExxonMobilChemical); Nordel™ IP 3670(a slightly crystalline,ethylene-propylene-diene terpolymer, that contains about 56.7-59.7% bymass ethylene by ASTM D3900, Dow Chemical Company); Nordel™ IP 5565 (anamorphous EPDM that contains about 50% by mass ethylene by ASTM D3900,Dow Chemical Company); Nordel™ IP 4520 (an amorphous, high diene, EPDMthat contains about 50% by mass ethylene by ASTM D3900, Dow ChemicalCompany); Buna® EP G 6850 (an ethylene-propylene-diene rubber (EPDM),amorphous; with ethylidene norbornene as termonomer and about 51% bymass ethylene according to ASTM D 3900, Lanxess Corporation); orRoyalene® 563 (an ethylene-propylene ethylidene norbornene rubber thatcontains about 57.3% ethylene, Lion Copolymer Geismar, LLC).

In some embodiments, the rubber backing layer 106 is prepared from arubber backing composition comprising one or more EPDMs in a range fromabout 20 wt % to about 60 wt %; about 25 wt % to about 55 wt %; about 30% to about 45 wt %; 30 wt % to about 40 wt %; 30 wt % to about 35 wt %;or about 34 wt % to about 36 wt % compared to the total weight of thefilled rubber backing composition.

In other embodiments, the EPDM is present in the rubber backingcomposition at about 40 wt % to about 70 wt %; about 45 wt % to about 65wt %; or about 50 wt % to about 60 wt % compared to the total weight ofthe filled rubber backing composition to allow for injection molding.This embodiment can allow for lower use of carbon black filler.

In some embodiments, the rubber backing layer 106 is prepared from arubber backing composition comprising from about 0.01 wt % to about 10wt % of a phenylenedimalemide; from about 0.1 wt % to about 5 wt %; fromabout 6 wt % to about 9 wt %; or from about 0.5 wt % to about 3 wt % ofa phenylenedimalemide. In some embodiments, the phenylenedimaleimide isN,N′-m-phenylenedimaleimide (CAS RN: 3006-93-7; N,N′-1,3-phenylenebismaleimide; HVA-2 curative, DuPont Chemical Co.). In another aspect ofan embodiment, the HVA-2 is present in the composition used to preparethe rubber backing layer at from about 0.1 wt % to 3 wt %; from 1% toabout 2% by weight; from about 1.01 wt % to about 1.5 wt % compared tothe total weight of the filled rubber backing composition.

The term “maleated compound” as used herein refers to a compound havingone or more, or two or more, maleic anhydride substituents. In someembodiments, the maleated compound is a maleated polybutadiene. Themaleated polybutadiene can be selected from a commercially availableproduct, such as Ricobond™, for example, Ricobond® 1756 HS(Polybutadiene adducted with maleic anhydride, Cray Valley USA), orPOLYVEST® MA 75 (a maleic anhydride adduct of a low molecular weight1,4-cis polybutadiene which has succinic anhydride groups randomlydistributed along the polymer chains, Evonik Corporation). In someembodiments, the maleated compound is present in the composition used toprepare the rubber backing layer 106 at from about 0.1 wt % to about 10wt %; from about 0.5 wt % to about 5 wt %; from about 7 wt % to about 9wt %; or from about 2 wt % to about 5 wt % compared to the total weightof the filled rubber backing composition. The maleated compound ispresent in the composition in order to achieve maximum level of bonding.In other aspects of an embodiment, the maleated compound is present inthe composition used to prepare the rubber backing layer 106 at about 3%to about 4% by weight. In still other aspects of an embodiment, themaleated compound is present in composition used to prepare the rubberbacking layer 106 at about 2% to about 6% by weight.

In some embodiments, the rubber backing layer 106 is prepared from arubber backing composition that further comprises fillers typicallyadded to EPDM rubbers. Examples of fillers used in some embodimentsinclude, for instance: silica, for example HiSil 243 LD™ (precipitatedamorphous silica from PPG Industries; Monroeville, Pa.); zinc oxide, forexample Kadox 930™ (zinc oxide, Zinc Corporation of America; Monaca,Pa.), Zano 20 (zinc oxide, Umicore Zinc Chemicals; Angleur, Belgium);calcium carbonate, for example Hubercarb Q325™ (ground calciumcarbonate, Akrochem Corp.; Akron, Ohio); talc, for example Mistron®vapor R (hydrous magnesium silicate, Imerys Talc), Nytal Talc (hydrousmagnesium silicate, R. T. Vanderbilt); carbon black, for exampleContinex™ N650 Carbon Black (carbon black, Continental Carbon; Houston,Texas), Vulcan® XC72R (powdered carbon black, Cabot Corp.; Billerica,Mass.),silicates, aluminum silicate, titanium dioxide, and stearic acid.

The rubber backing composition has the advantage of allowing for highfiller load, providing a more economical composition. In someembodiments the filler comprises from about 30 % to about 65 % by weightof the composition used to prepare the rubber backing layer. In otheraspects of an embodiment, the filler comprises from about 30 wt % toabout 60 wt %; from about 40 wt % to about 60 wt %; from about 45 w t%to about 60 wt %; from about 45 wt % to about 55 wt %; or from about 45wt % to about 50 wt % compared to the total weight of the filled rubberbacking composition.

In some embodiments, the rubber backing layer 106 is prepared from arubber backing composition further comprising plasticizers. Exampleplasticizers used in some embodiments include polymer based types, suchas polybutene, or paraffinic oils such as Sunpar 2280 DLC-A™ (paraffinicprocess oil silicon dioxide blend plasticizer, Natrochem Inc.), Drakeol®mineral oil (white mineral oil, Calumet Penreco; Dallas, Tx.), PD-23White Oil (white mineral oil, Sonneborn, Inc.; Tarrytown, N.Y.) . Insome embodiments, the plasticizer is present at from about 0.1 wt % toabout 25 wt %; about 1 wt % to about 20 wt %; about 5 wt % to about 15wt %; about 7 wt % to about 12 wt %; about 8 wt % to about 10 wt %;about 9 wt % to about 11 wt %; or from about 9 wt % to about 10.5 wt %by weight of the composition used to prepare the rubber backing layer.

In some embodiments, the rubber backing layer 106 is prepared from arubber backing composition further comprising a peroxidic vulcanizingagent. Examples of peroxides used in some embodiments include, forinstance: dicumyl peroxide, di-t-butyl peroxide, and t-butyl cumylperoxide, and commercial products, such as Luperox™ DC40P-SP2 (dicumylperoxide extended on calcium carbonate and silica, Arkema) or Varox®DCP-99 (bis(1-methyl-1-phenylethyl) peroxide, R. T. Vanderbilt). In someembodiments, an efficient peroxide, such as a dicumyl peroxide, ispreferable. In some embodiments, the peroxide is present at about 0.1 wt% to about 5 wt %; at about 1 wt % to about 4 wt %; at about 2 wt % toabout 3 wt %; at about 1.5 wt % to about 2.5 wt %; at about 1.5 wt % toabout 4 wt %; or at about 0.1 wt % to about 3 wt % by weight of thecomposition used to prepare the rubber backing layer. In someembodiments, because HVA-2 is a reactive Type I co-agent that increasesreaction rate and state of cure, any efficient peroxide, such as adicumyl peroxide, is employed in the rubber backing composition toensure consistent free radical formation occurs.

In one embodiment, the rubber backing layer 106 is prepared from arubber backing composition further comprising an antioxidant. Examplesof antioxidants used in some embodiments include, for instance, AgeriteMA™ (2,2,4-trimethyl-1,2-dihydroquinolone polymer) or Irgafos® 168 (tris(2,4-di-tert-butylphenyl)phosphite, Ciba). In some embodiments, theantioxidant is present at about 0.01 wt % to about 5 wt % by weight ofthe rubber backing layer composition. In other aspects of an embodiment,the antioxidant is present at about 0.05 wt % to about 3 wt %; 0.1 wt %to about 1.5 wt; or from about 0.1 wt % to about 1.0 wt % by weight ofthe composition used to prepare the rubber backing layer.

The rubber backing compositions provided herein are capable of a dualbonding mechanism for direct bonding to the polyamide layer without anintervening adhesive layer. The maleimide groups are capable of formingcovalent C—C interactions with the carbon backbones of both the EPDMpolymer and also the polyamide. Similarly, a possible bonding mechanismbetween the EPDM and the MA is through a C—C bond.

Surprisingly, one embodiment of the rubber backing layer 106 hasdemonstrated superior cold temperature performance. In contrast to othercommercial formulations, such as Santoprene®, which shows leakage below10° C., Example 7 of the rubber backing layer 106 unexpectedly extendsthe cold temperature range of the hose down to −40° C. to −60° C.Santoprene® is a thermoplastic elastomer that is a mixture of in situcrosslinking of EPDM rubber and polypropylene. In some embodiments, therubber backing layer 106 is prepared from an EPDM composition that doesnot contain polypropylene. One example of cold temperature performanceis described in more detail below with reference to Example 6.

Additionally, embodiments of the hose provided herein have demonstratedsuperior high temperature capability as compared to commercial productGH134. For example, the butyl backing layer in GH134 hose has a maximumhigh temperature capability of 120° C. In contrast, one embodiment ofthe hose provided herein, (Example 9, GH001) has an EPDM rubber backinglayer with a maximum high temperature capability of 150° C.Additionally, the chlorobutyl cover of GH134 has a maximum hightemperature capability of 120° C. An example embodiment of the hoseprovided herein, Example 7, has an EPDM cover with a maximum temperaturecapability of high 150° C. Thus, an example embodiment of the hoseprovided herein has a 30-degree increase in temperature capability.

The hose of FIG. 1 comprises a polyamide layer 104 in order to impartpermeation resistance to the hose. The polyamide layer 104 is directlybonded, via the dual bonding mechanism, to the rubber backing layer 106upon cure. In some embodiments, the polyamide layer 104 is prepared froma composition comprising PA6,6 and/or PA6. In some embodiments, thepolyamide layer is prepared from a composition comprising PA 6,6. Thepolyamide layer 104 is a distinct layer from the rubber backing layer106. That is, the components of the polyamide layer 104 are not presentin the rubber backing layer 106. The polyamide layer 104 is a continuouslayer.

In some embodiments, the polyamide layer 104 comprises a polyamidemolding component that contains amide —CO—NH- bonds in its main chainand additives. The polyamides are prepared in a known manner bypolycondensation. In some embodiments, the polyamide is selected from apolyamide wherein the ratio between the COOH and NH2 groups in thepolyamide is preferably 1:x where 1<x<100. In some embodiments, heatstabilized polyamide resins are suitable. Examples of suitable nylonpolyamides include PA 46 (polyamide 46; nylon 46), PA 6 (polyamide 6;nylon 6), PA 6,6 (polyamide 6,6; nylon 6,6), PA 11 (polyamide 11, nylon11), PA 12 (polyamide 12; nylon 12), PA 612 (polyamide 612; nylon 6,12),and PA 610 (polyamide 610; nylon 6,10). In some embodiments, suitablenylon polyamides include PA 6, PA 6,6, PA 12 and PA 11. In still otherembodiments, suitable nylon polyamides include PA 6 and PA 6,6. In yetother embodiments, suitable nylon polyamides include PA 6,6. In someembodiments, the polyamide layer 104 is prepared from a commerciallyavailable product, such as DuPont Zytel® 45HSB PA 6,6. In someembodiments, the polyamide layer 104 is from about 0.001″ to about 0.01″thick; or from about 0.002″ to about 0.008″ thick. In some embodiments,the polyamide layer 104 is from about 0.003″ to about 0.005″ thick.

In some embodiments, the polyamide layer 104 is prepared from apolyamide composition further comprising additives such as reinforcingagents, flameproofing agents, stabilizers, processing auxiliaries,blowing agents, metal fibers, carbon black, graphite and metal leaf,titanium dioxide, colored pigments and zinc sulfide.

The hose of FIG. 1 comprises an inner resistance layer 102 forresistance to moisture ingression and oils. In some embodiments, theresistance layer 102 is prepared from a composition comprising apolyamide. In specific embodiments, the resistance layer 102 is preparedfrom a composition comprising PA 6, PA 6/12, PA 11, or PA 12. In someembodiments, PA 6 or PA 6/12 are used in the preparation of theresistance layer 102 because of their ability to directly bond to PA6,6. In some embodiments, the resistance layer is a commerciallyavailable material, for example, DuPont Zytel® FN727. In otherembodiments, the resistance layer 102 is prepared from a fluorinatedpolymer. In some embodiments, the fluorinated polymer is, for example,polyvinylidene fluoride (PVDF). In some embodiments, the resistancelayer 102 is used as an oil barrier. In some embodiments, the resistancelayer 102 is from about 0.006″ to about 0.01″ thick; from about 0.007″to about 0.008″ thick; from about 0.007″ to about 0.009″ thick; or fromabout 0.0065″ to about 0.0085″ thick.

In some embodiments, the resistance layer 102 and the polyamide layer104 are formed by coextruding PA6 and PA 6,6 to form a plastic veneer.

In the hose of FIG. 1, the polyamide layer 104 and the rubber backinglayer 106 are chemically covalently bonded together without the use ofadhesive. In one embodiment, the rubber backing layer 106, prepared froma composition comprising EPDM, MAH, and HVA-2, bonds directly to thepolyamide layer 104 comprising nylon 6,6 upon cure. Although the exactbonding mechanism between the layers is unclear, a possible bondingmechanism, which occurs through, for example, traditional press cure orextrusion processing methods exploits two different mechanisms. First,the MA might bond to the amine end of nylon 6,6 forming a C—N bond byDiels-Alder chemistry. Second, the cyclic carbon on the maleimide groupsmight form covalent C—C interactions to the nylon 6,6 backbone throughan “Alder-ene” reaction using a free radical mechanism. In oneembodiment, the polyamide layer 104 and the rubber backing layer 106undergo shearing and vulcanization at a temperature of about 300-350° F.

The cover layer 110 has the largest outer diameter of the layers. Insome embodiments, the cover layer 110 comprises a rubber, for example,EPDM. In a preferred embodiment, the cover layer is prepared from acomposition comprising an EPDM compound capable of maintaining a seal atlow temperatures. In some embodiments the EPDM is made with low ethyleneso it has low temperature capability. In some embodiments, the coverlayer comprises a peroxide cured EPDM made with low ethylene content. Insome embodiments, there is no adhesive between the cover layer 110 andthe reinforcement layer 108. The reinforcement layer 108 comprises atextile. Examples of suitable textiles for the reinforcement layer 108include aramid, polyester braid, nylon, cotton, and rayon. In someembodiments, the reinforcement layer 108 is a discontinuous layer. Insome embodiments, the reinforcement layer 108 is a discontinuous layercomprising a polyester braid, aramid, nylon, cotton, or rayon. In someembodiments, the cover layer 110 and the rubber backing layer 106,migrate through the interstices of the textile in the reinforcementlayer 108 and vulcanize together.

In some embodiments, the hose comprises five layers. In one embodiment,the inner diameter of the hose resistance layer 102, the innermostlayer, is 0.585″ ±0.015″. In other embodiments, the inner diameter ofthe resistance layer 102 is 0.705″ ±0.015″. In still other embodiments,the inner diameter of the resistance layer 102 is 0.785″ ±0.015″. In yetother embodiments, the inner diameter of the resistance layer 102 is0.975″ ±0.015″.

EXAMPLES

A hose according to the invention, comprising a rubber backing layerthat directly bonds to a polyamide permeation veneer, was developed forautomotive use. EPDM was selected for use as the base thermoplasticelastomer polymer for use in preparation of the rubber backing layer 106of the hose in order to maintain heat resistance upwards of 160° C.while simultaneously maintaining the low temperature sealing capability(−50° C.) desirable for a refrigerant hose.

Compression set (C Set) is one of the primary characteristics of arubber compound directing low temperature sealing capability. EPDMethylene content is the primary factor influencing this compressioneffect. As the ethylene content increases, a low-level of crystallinitydevelops above 55%-65%. If the ethylene/propylene ratio is about equaland the distribution of both monomers in the polymer chain is randomthen the EPDM is amorphous. Polymers with ethylene content above 60%tend to show high compression set, while the amorphous (less than 60%ethylene) materials provide decreased set values at low temperatures.

A Banbury™ mixer (Farrel Corporation) was used to mix the differentrubber formulations according to ASTM D 3182-07. First, the polymer wasadded first into the mixer in a 30 second mastication cycle at 150° C.Second, fillers and oils were added in a 120 second mix cycle at 200° C.Then, process aids, such as vulcanizing agents, were added in a 120second mix cycle at 220° C. Fourth, the composition undergoes a fourthmix cycle for 90 seconds at 220° C.

Then the master batch rubber is inserted into the mixer with thecuratives and mixed for 120 seconds at 180° C., followed by a final mixfor 120 seconds at 180° C.

After the rubber drops from the mixer, the rubber was manually appliedto a dual-roll mill and sheeted until the thickness is 0.75″-1.25″,according to ASTM B 947-06. The dual roller mill stage sheets and coolsthe mixed formulation.

The cure kinetics of the rubber formulations were assessed according toASTM D 2084-95 (cure study). Rheometry was measured using a MonsantoRPA2000 for 45 minutes at 160° C.

The sheeted material then was subjected to the cure press forvulcanization. Based on T90 values from the cure study, the sheetedmaterial from the dual roller mill was inserted into the cure press andvulcanized at 320° F. for 45 minutes.

Next, the rubber underwent a Shore A hardness test. In accordance withASTM D 2240-95, the hardness was tested using a calibrated Instronautomatic Durometer tester. The compression set was tested in accordancewith ASTM D 395-89. The sample was prepared as follows. First, the EPDMrubber was vulcanized for 60 minutes at 320° F. into 0.49″ thick by1.14″ diameter buttons. Then the buttons were compressed by 25% into a CSet fixture. After curing, the samples were exposed at −40° C. for 24hours and samples were removed and measured at specified timeincrements. The time versus percent compression was then plotted on agraph, shown in FIG. 9. Last, the overall compression set was assessedon a sample that was allowed to run the full 24 hours and then reboundat room temperature outside of the C Set fixture prior to the finalmeasurement.

The strip adhesion test was conducted in accordance with ASTM D 413-81.This test measured the adhesion strength between various embodiments ofthe rubber backing layer with an embodiment of the polyamide layer.Specimen Type B—90° peel was used. The sample was prepared usingpolyamide 6,6 injection molded samples that were 4″ long, 1″ wide, and0.075″ thick. The PA 6,6 samples were laid on top of rubber samples thatwere 4″ long, 1″ wide and 0.09″ thick, on a standard press cure. Thesamples were vulcanized for 45 minutes at 320° F. Twenty-four hoursafter vulcanization, the samples were tested on a calibrated Instron5965 (according to ASTM D413 Type B (90° C. peel)) using a 5 KN loadcell at a rate of 2″/min. Tensile strength and percent elongation weretested in accordance with ASTM 412. Standard ASTM samples were tested ona calibrated Instron 5965 using a 5 KN load cell at a rate of 20″/min.

The Green Rubber Shelf Life test evaluated how the measurements changedover time. Samples were cured at time intervals over 3 months (45″ at320° F.) from a standard uncured stock. Those samples underwent testsaccording to ASTM 412, ASTM D 2084-95, and ASTM D 413-81.

Permeation of test hose and comparative product hose Y was tested inaccordance with SAE J2064. Samples were stabilized for 24 hours at 23°C. ±2° C. before testing and checked to ensure specified charge andidentify charge loss.

Example 1 Strip Adhesion between Rubber Backing and PolyamideLayers—Bonding Effect Factors.

To investigate the bonding effect between embodiments of the rubberbacking and polyamide layers, sixteen different mixes were tested usinga maleated compound comprising silica grafted with maleic anhydride(MA), HVA-2 (phenylenedimaleimide) and two EPDM polymers with similarethylidene norbornene (ENB) and ethylene percentages but varying (highand low) viscosities. The results for strip adhesion (ASTM D413) aredisplayed in the Pareto chart of FIG. 2. The alpha for the Pareto chartis 0.04. The data show that factors that extend beyond an effect of 2.45had a significant effect on adhesion.

The data suggest that the primary factor affecting adhesion is theHVA-2, followed by polymer viscosity, maleic anhydride content and thensome insignificant synergistic relationships between the mentionedreagents.

The plots in FIG. 3 depict main effects plots for adhesion, showing thedata means of the sixteen mixes of Example 1. The data in FIG. 3 showthat HVA-2 and maleic anhydride inclusion results in increasing rubberto plastic adhesion while increasing polymer viscosity has an inverserelationship to substrate bonding. These statements are made byobservation of direction and severity of plot slope for each result asconcentration is increased.

Example 2 Strip Adhesion Between Rubber Backing and Polyamidelayers-HVA-2 Titration

A regression analysis was next performed by titrating T(MPBM) D-70 HVA-2reagent from 0 pph to 5 pph and testing for adhesion to PA 6,6.Afterwards, the results for HVA-2 (pph) versus adhesion (lbf/in) wereplotted in a quadratic manner in FIG. 4. The data are fitted with aregression fitted line, the quadratic equation beingAdhesion=3.682+6.810(HVA-2)−0.6668(HVA-2)^2. The R2 of the fit is 92.9%and the adjusted R2 of the fit is 88.2%. The residual standard deviationis 2.40567.

The curve details the saturation kinetics associated with the freeradical phenylenedimaleimide reaction whereby the cyclic carbon on themaleimide groups form covalent C-C interactions with the carbonbackbones of both the EPDM polymer and also the polyamide.

Example 3 Strip Adhesion between Rubber Backing and Polyamidelayers-Maleated Compound Titration.

The effect of varying the maleated compound content was assessed througha regression analysis where the amount of an example maleated compound,Ricobond® 1756 HS, was increased from 0 pph to 20 pph through fiveexperimental formulations. All other reagents including HVA-2 were heldconstant. Afterwards, the results for the maleated compound (pph) versusadhesion (lbf/in) were plotted in a quadratic manner in FIG. 5. The dataare fitted with a regression fitted line, the quadratic equation beingAdhesion=17.07 +1.088(Ricobond® 1756 HS)−0.03554(Ricobond® 1756 HS)^.The R2 of the fit is 96.1% and the adjusted R2 of the fit is 94.2%. Theresidual standard deviation is 0.819977.

The results for adhesion in FIG. 5 suggest that saturation of the maleicanhydride reaction to the polyamide n-terminal amine occurred somewherearound 10 pph.

Note that at 0 pph there is already about 16 lbf/in of adhesive forcedue to the presence of 3 pph HVA-2 and the final saturated adhesion wasfound to be about 24 lbf/in. This validates the hypothesis that theHVA-2 and maleic anhydride reactions are non-competitive and generate a“compounding” effect since an additional 8 lbf/in is generated above theHVA-2 saturation level. This makes sense because HVA-2 forms a covalentbond (C—C bond) with the carbon backbone of the polyamide while maleicanhydride interacts with the polyamide N-terminal amine group (C—Nbond).

Example 4 Strip Adhesion between Rubber Backing and Polyamidelayers-Effect of Plasticizers and Fillers

Example 4 investigated the effects of other standard reagents,plasticizer and carbon black fillers, on adhesion quality. Plasticizersused in this study include both paraffinic and a polymer based(polybutene) types. While paraffinic plasticizers such as Lubspar 2280are generally used in EPDM compounds, there is some concern that itmight affect adhesion by blooming to the surface of the rubber andruining the rubber/plastic interface. Conversely, polymeric plasticizersgenerally do not migrate through the rubber resulting in accumulation atthe material surface. They are however more expensive and difficult tomanipulate at the production level due to their very high 14230 SUSviscosity versus paraffinic oil (2582 SUS).

The results for strip adhesion (ASTM D413) are displayed in the Paretochart of FIG. 6. The response is adhesion and the alpha for the Paretochart is 0.05. Factors that extend beyond an effect of 2.31 had asignificant effect on adhesion. The results depicted in FIG. 6 implythat both forms of plasticizer affect adhesion to an equal extent andtogether exert a significant response in comparison to the filleradditions.

FIG. 7 is the main effects visual chart of Example 4 for adhesion. Thedata in FIG. 7 show that the plasticizer effects are equal and necessarysince increasing amounts have a direct correlation on improved adhesionvalues.

Additionally, this data set suggests that carbon black type and amounthas minimal effect on rubber to plastic adhesion. In Example 7, theLubspar/Sunpar paraffinic type oil was used because it is easier tohandle, numerous suppliers exist and it has a favorable price incomparison to the polybutene plasticizer.

Example 5 Shelf Life of Rubber Backing Layer Green Material

Examples 1-5 identified the type and amount of reagents used in anembodiment of the rubber backing layer. Another study was performed toinvestigate shelf life of an uncured embodiment of the rubber backinglayer, Example AB. “Green” samples were intermittently removed from theproduction lot and cured over a two month period according to ASTM D3182(45 minutes at 320° F.). Additionally, strips of injection molded PA 6,6were applied to half of the sheet rubber and tested according to ASTM413-81 for strip adhesion.

The results plotted in FIG. 8 imply that shelf life of an embodiment ofthe rubber backing layer, AB, is good for 45 days because until 45 dayselapses, the tensile strength and percent elongation lose less than 25%versus the original time zero values. After 45 days the material losessignificant amounts of its physical properties. Interestingly, while thephysical properties declined, the bonding capability remained the samethroughout the 60 day trial.

Example 6 Compression Set Properties of Rubber Backing Layer

A backing layer compression experiment was performed to assess the cold(−40° C.) compression set properties of the rubber backing layer. Acured layer according to Example 7 was tested according to ASTM 395, tovalidate its sealing capability, and to compare cold compression setproperties to two different control backing layers of comparativeproducts AC and AD. The results are depicted in FIG. 9. Hypothetically,since the polymer ethylene level of AB (50%) is the same as the ADcompound (low temperature coolant tube or cover), the cold compressionshould be equivalent. However, this was not the case. Also tested was alow temperature compression control, AC, which is a standard 70%ethylene EPDM formulation. After either platen or steam curing, thesamples were exposed to −40° C. for 24 hours according to ASTM 395-89,removed from the C set fixture and measured at time intervals up to 30minutes. The test measures the % rebound as a function of time. Anincreased rate is indicative of faster material recovery during warmingcycle.

FIG. 9 characterizes this phenomenon by plotting the kinetics of percentcompression versus time. The data suggest that a rubber backing layeraccording to Example 7 following cure of, Test AB, compares well tocomparative GH134 backing layer compression of AD since both rebound ata rate of about 35% faster based on calculated slopes than the ACcontrol compound.

Example 7 Rubber Backing Compositions

The following Example 7 rubber backing composition was preparedaccording to the protocols above.

TABLE 1 Rubber Backing Composition A. Ingredients Component PPH %Content Grams Vistalon 2504 EPDM 100.00 34.42 499.14 Hubercarb Q 325calcium carbonate 15.00 5.16 74.87 MISTRON VAPOR R talc 10.00 3.44 49.91HI-SIL 243 LD silicon dioxide, amorphous 20.00 6.88 99.83 LUBSPAR 2280paraffinic process oil (SUNPAR 2280) silicon dioxide blend plasticizer30.00 10.33 149.74 KADOX 930 zinc oxide 5.00 1.72 24.96 AGERITE MAantioxidant 1.00 0.34 4.99 T(MPBM)D-70 HVA-2 3.00 1.03 14.97 RICOBOND1756 HS maleated polybutadiene 10.00 3.44 49.91 N650 BLACK carbon black90.00 30.98 449.23 LUPEROX DCP-40P-SP2 dicumyl peroxide 6.50 2.24 32.44Totals: 290.5 100 1450

The rubber backing layer prepared from Example 7 rubber backingcomposition A exhibited desirable characteristics upon cure. Using amoving die rheometer at 157° C., 0.5 Arc, 100 cpm, and 30 minutes, therubber backing layer prepared according to Example 7 had a T5 of 5 min;a Mooney viscosity of 41MU; adhesion greater than 10 lbf/in; tensilestrength 1,472 psi; elongation 148% and cost $1.35/lb. In addition, thebacking layer prepared from Example 7 rubber backing composition Aexhibited desirable direct bonding to polyamide 6,6 veneer, andmulti-refrigerant/oil compatibility.

Example 8 Cover Layer Composition

The following Example 8 cover layer composition was prepared accordingto the protocols above.

TABLE 2 Cover Layer Composition. Ingredients Component PPH % ContentGrams BUNA EP G 6850 EPDM 100.00 34.63 502.16 N650 BLACK Carbon black85.00 29.44 426.84 PELLETIZED N990 BLACK Carbon black 35.00 12.12 175.76HI-SIL 243LD silicon dioxide, amorphous 10.00 3.46 50.22 SUNPAR 2280paraffinic process oil silicon dioxide 40.00 13.85 200.87 blendplasticizer F-2000 STEARIC ACID Stearic Acid 1.00 0.35 5.02 ANTIOXIDANTDQ Antioxidant 1.50 0.52 7.53 MAGCHEM HSA-10 Magnesium oxide 5.00 1.7325.11 REDIMIX 9595 Oil-treated powder 0.55 0.19 2.76 VUL-CUP 40KEbenzoyl peroxide crosslinking agent 1.50 0.52 7.53 SARET SR633 zincdiacrylate 2.20 0.76 11.05 VAROX DBPH-50-HP dicumyl peroxide 7.00 2.4235.15 Totals: 288.75 100 1450

As shown in Table 2, the cover layer was prepared using the followingingredients: Buna® EP G 6850 (an ethylene-propylene-diene rubber (EPDM),amorphous; with ethylidene norbornene as termonomer and about 51% bymass ethylene according to ASTM D 3900, Lanxess Corporation); N650 BlackPelletized (Carbon Black, Cabot); N990 Black (Carbon Black, Cancarb);Hi-Si1243D (precipitated amorphous silica from PPG Industries;Monroeville, Pa.); Sunpar 2280 (paraffinic process oil silicon dioxideblend plasticizer, Natrochem Inc.); F-2000 Stearic Acid (stearic acidand palmitic acid, Harwick Standard Distribution Corporation);Antioxidant DQ (polymerized 2,2,4-trimethyl-1,2-dihydroquinoline,Akrochem Corp.); Magchem HSA-10 (magnesium oxide, Martin Marietta);Redimix 9595 (oil-treated powder, Hexpol Compounding); Vul-cup 40KE(benzoyl peroxide crosslinking agent, Hercules Inc.); Saret SR633(anhydrous zinc diacrylate, Sartomer); and Varox DBPH-50-HP(2,5-Dimetyl-2,5-di(t-butylperoxy)-hexane, R.T. Vanderbilt Company,Inc.).

Example 9 Hose Comprising Rubber Backing Layer directly bonded to aPolyamide Layer.

A hose was prepared according to the invention comprising an innerresistance layer comprising PA6; a polyamide layer comprising PA 6,6directly bonded to; a rubber backing layer prepared from rubber backingcomposition A, Example 7; a reinforcement layer; and an outer coverlayer prepared from a composition according to Example 8. PA6 and PA6,6were co-extruded on mandrel to make veneer. The Backing layer wasextruded on top of veneer.

The Braid Reinforcement layer was applied and the Cover layer wasextruded over the braid. The assembly was subjected to Vulcanization andthe Mandrel was expelled from the hose construct.

The resultant hose, GH001, has a PA6 oil barrier 102, followed by aPA6,6 permeation layer 104, then a direct bond EPDM rubber backing layer106 according to Example 7 with max temp of 150° C., then a polyesterbraid 108, and finally an EPDM cover layer 110 (max 150° C.) accordingto Example 8. The EPDM and lack of adhesive give GH001 a temperaturecapability of 150° C.

Example 10 Hose Permeation Testing.

The test hose of Example 9 GH001 was compared to commercially availableGH134 hose and tested with refrigerant gases R-134a and R1234-yf. Inthis example, test hose product X, GH001, was compared to comparativehose product Y, a GH134 hose. GH134 has a PA6 oil barrier as the innerlayer, then a butyl backing layer is adhered to the oil barrier layerwith Robond™ adhesive, then a polyester braid as a reinforcement layerand a chlorobutyl cover layer (max 120° C.). As noted above, the examplerubber formulation of Example 7 demonstrated other improved qualities,such as a temperature capability that is thirty degrees higher thanGH134. The tests were performed in accordance with SAE J2064.

Specifically, the charged samples were stabilized for 24 hours at 23° C.±2° C. prior to testing. The test specimens consisted of four coupledhose assemblies that have 107 cm±1.2 cm of exposed hose betweencouplings. Three of the coupled hose assemblies were used fordetermining the permeation rate through the test and control hoses ofrefrigerants R-134a and R1234-yf at specific temperatures. The fourthcoupled and plugged hose assembly was used for a control hose. One endof each hose assembly was attached to a canister. The other end wascapped with a plug. The coupled hose assemblies were weighed andrecorded to 0.01 g to establish an initial weight prior to charging. Thetest samples were evacuated and then charged with refrigerant to 70%±3%of the internal volume of the assembly and then reweighed. The weightswere taken at room temperature. The test temperature was 80° C.±2° C.The samples were weighed at the end of the first 24 hour temperatureexposure and at period intervals. The weighings were reported in netloss of grams, calculated by charged sample weight loss minus controlsample weight loss. The net weight loss versus time was recorded for 25days.

Conversion factors were then used to calculate the kg/m2/year rate ofpermeability.

Test hose X, GH001, when tested according to SAE J2064, had a permeationvalue of 2 kg/m2/yr for refrigerant R-134a. When tested according to thesame SAE standard, the comparable rubber formulation, comparativeproduct Y, GH134, had a permeation value of 5.5 kg/m2/yr for refrigerantR-134a. R-134a is 1,1,1,2-tetrafluoroethane, also known as Genetron134a, Suva 134a, and HFC-134a. R-1234-yf, a newer refrigerant, was alsotested. R-1234-yf is 2,3,3,3-tetrafluoropropene, also known asHFO-1234yf and 2,3,3,3-tetrafluoropropylene. Using the newer, differentrefrigerant, R1234-yf, example rubber formulation X, when testedaccording to SAE J2064, had a permeation value of 1.2 kg/m2/yr. Whentested according to the same SAE standard, the comparable rubberformulation, comparative product Y, had a permeation value of 3.5kg/m2/yr for refrigerant R-1234-yf. It is therefore clear that exampleproduct X, GH001, comprising an embodiment of the rubber backing layer,exhibits at least a two-fold improvement in permeability compared toGH134 hose. The results are depicted in Table 3 below.

TABLE 3 Permeation of test hose, GH001, product X, and comparativecontrol hose, GH134, product Y, to refrigerants R-134a and R1234-yfaccording to SAE J2064. Hose Refrigerant Permeation Comparative productY R-134a 5.5 kg/m²/yr Example rubber formulation X R-134a 2 kg/m²/yrComparative product Y R1234-yf 3.5 kg/m²/yr Example rubber formulation XR1234-yf 1.2 kg/m²/yr

Although the invention has been described and has been illustrated inconnection with certain specific or preferred inventive embodiments, itwill be understood by those of skill in the art that the invention iscapable of many further modifications. This application is intended tocover any and all variations, uses, or adaptations of the invention thatfollow, in general, the principles of the invention and includedepartures from the disclosure that come within known or customarypractice within the art and as may be applied to the essential featuresdescribed in this application and in the scope of the appended claims.

1-32. (canceled)
 33. A method of making a hose, comprising: coextrudingtwo or more polyamide layers onto a mandrel to form a veneer comprisingan inner resistance layer and a polyamide layer; blending a firstcomposition comprising an ethylene propylene diene monomer (EPDM), amaleated compound, and a phenylenedimalemide and extruding the firstcomposition on top of the polyamide layer to form a rubber backinglayer; applying a reinforcement layer over the rubber backing layer;extruding a cover layer over the reinforcement layer to form a greenhose; vulcanizing the green hose to form a cured hose; and expelling thecured hose from the mandrel.
 34. The method of claim 33, wherein saidextrusion comprises shearing and heating.
 35. The method of claim 33,wherein said vulcanizing occurs at 300-350° F.
 36. The method of claim35, wherein said vulcanizing occurs for a period of at least 45 minutes.37. The method of claim 36, wherein said vulcanizing occurs for a periodof at least 60 minutes.
 38. The method of claim 33, wherein saidcoextruding comprises coextruding a PA6 and a PA6,6 on the mandrel tomake the veneer.
 39. The method of claim 33, wherein the firstcomposition comprises the EPDM within a range of from about 20 wt % toabout 60 wt % compared to the total weight of the first composition. 40.The method of claim 33, wherein the first composition comprises thephenylenedimaleimide within a range of from about 0.01 wt % to about 10wt % of the total weight of the first composition.
 41. The method ofclaim 40, wherein the phenylenedimaleimide isN,N′-m-phenylenedimaleimide.
 42. The method of claim 33, wherein thefirst composition comprises the maleated compound within a range of fromabout 0.1 wt % to about 10 wt % of the total weight of the firstcomposition.
 43. The method of claim 42, wherein the maleated compoundis a maleated polybutadiene.
 44. The method of claim 33, wherein thefirst composition further comprises a plasticizer.
 45. The method ofclaim 44, wherein the plasticizer is present in the first compositionwithin a range of from about 0.1 wt % to about 25 wt % of the totalweight of the first composition.
 46. The method of claim 45, wherein theplasticizer is selected from the group consisting of a polybutene, amineral oil, a paraffinic plasticizer, and a paraffinic process oilsilicon dioxide blend plasticizer.
 47. The method of claim 33, whereinthe first composition further comprises a filler.
 48. The method ofclaim 47, wherein the filler is present within a range of from about 30wt % to about 60 wt % compared to the total weight of the firstcomposition.
 49. The method of claim 48, wherein the filler comprisesone or more fillers selected from the group consisting of carbon black,silica, silicates, talc, aluminum silicate, calcium carbonate, zincoxide, titanium dioxide and stearic acid.
 50. The method of claim 33,wherein the first composition further comprises an antioxidant within arange of from about 0.05 wt % to about 3 wt % compared to the totalweight of the first composition.
 51. The method of claim 33, wherein thefirst composition further comprises an organic peroxide within a rangeof from about 0.1 wt % to about 5 wt % compared to the total weight ofthe first composition.
 52. The method of claim 51, wherein the organicperoxide is selected from the group consisting of dicumyl peroxide andt-butyl cumyl peroxide.
 53. The method of claim 33, wherein thepolyamide layer is prepared from a second composition comprising one ormore of the group consisting of polyamide 6,6; polyamide 6; andpolyamide 6/12.
 54. The method of claim 33, wherein the rubber backinglayer of the cured hose exhibits adhesion to the polyamide layer ofgreater than 10 lbf/in, when tested according to ASTM D413.
 55. Themethod of claim 33, wherein the cured hose exhibits a permeation valueof less than 3 kg/m²/yr for a refrigerant selected from the groupconsisting of R134a (1,1,2-tetrafluoroethane) and R-1234-yf(2,3,3,3-tetrafluoropropene) when tested according to SAE J2064 at 80°C. +/−2° C.
 56. The method of claim 55, wherein the cured hose exhibitsa permeation value of less than 2 kg/m²/yr for a refrigerant selectedfrom the group consisting of R134a (1,1,2-tetrafluoroethane) andR-1234-yf (2,3,3,3-tetrafluoropropene) when tested according to SAEJ2064 at 80° C. +/−2° C.
 57. The method of claim 33, wherein the hosecomprises the following distinct layers in the hose's radial directionfrom the outside inwards: the cover layer; the reinforcement layer; therubber backing layer; the polyamide layer; and the resistance layer.